Return the start error and reap

Make sure that if we get an error from start it is returned and that we
reap the container's process from create before existing if we were to
send a kill signal.

Signed-off-by: Michael Crosby <crosbymichael@gmail.com>

containerd-shim/main.go

@@ -17,6 +17,12 @@ func writeMessage(f *os.File, level string, err error) {
 	fmt.Fprintf(f, `{"level": "%s","msg": "%s"}`, level, err)
 }
 
+type controlMessage struct {
+	Type   int
+	Width  int
+	Height int
+}
+
 // containerd-shim is a small shim that sits in front of a runtime implementation
 // that allows it to be repartented to init and handle reattach from the caller.
 //
@@ -82,13 +88,40 @@ func start(log *os.File) error {
 		p.delete()
 		return err
 	}
+	msgC := make(chan controlMessage, 32)
 	go func() {
 		for {
-			var msg, w, h int
-			if _, err := fmt.Fscanf(control, "%d %d %d\n", &msg, &w, &h); err != nil {
+			var m controlMessage
+			if _, err := fmt.Fscanf(control, "%d %d %d\n", &m.Type, &m.Width, &m.Height); err != nil {
 				continue
 			}
-			switch msg {
+			msgC <- m
+		}
+	}()
+	var exitShim bool
+	for {
+		select {
+		case s := <-signals:
+			switch s {
+			case syscall.SIGCHLD:
+				exits, _ := osutils.Reap()
+				for _, e := range exits {
+					// check to see if runtime is one of the processes that has exited
+					if e.Pid == p.pid() {
+						exitShim = true
+						writeInt("exitStatus", e.Status)
+					}
+				}
+			}
+			// runtime has exited so the shim can also exit
+			if exitShim {
+				ioutil.WriteFile(fmt.Sprintf("/tmp/shim-delete-%d", p.pid()), []byte("deleting"), 0600)
+				p.delete()
+				p.Wait()
+				return nil
+			}
+		case msg := <-msgC:
+			switch msg.Type {
 			case 0:
 				// close stdin
 				if p.stdinCloser != nil {
@@ -99,38 +132,19 @@ func start(log *os.File) error {
 					continue
 				}
 				ws := term.Winsize{
-					Width:  uint16(w),
-					Height: uint16(h),
+					Width:  uint16(msg.Width),
+					Height: uint16(msg.Height),
 				}
 				term.SetWinsize(p.console.Fd(), &ws)
 			case 2:
 				// tell runtime to execute the init process
 				if err := p.start(); err != nil {
-					syscall.Kill(p.pid(), syscall.SIGKILL)
+					p.delete()
+					p.Wait()
+					return err
 				}
 			}
 		}
-	}()
-	var exitShim bool
-	for s := range signals {
-		switch s {
-		case syscall.SIGCHLD:
-			exits, _ := osutils.Reap()
-			for _, e := range exits {
-				// check to see if runtime is one of the processes that has exited
-				if e.Pid == p.pid() {
-					exitShim = true
-					writeInt("exitStatus", e.Status)
-				}
-			}
-		}
-		// runtime has exited so the shim can also exit
-		if exitShim {
-			ioutil.WriteFile(fmt.Sprintf("/tmp/shim-delete-%d", p.pid()), []byte("deleting"), 0600)
-			p.delete()
-			p.Wait()
-			return nil
-		}
 	}
 	return nil
 }